<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>手写instanceof</title>
</head>

<body>
    <script>
        function myInstanceof(left, right) {
            var prototype = right.prototype;
            var left = left.__proto__;
            while (true) {
                if (left === null || left === undefined) {
                    return false;
                }
                if (left === prototype) {
                    return true;
                }
                left = left.__proto__;
            }
        }
    </script>
</body>

</html>